Wire bootstrap-producer into the Antithesis compose stack

[paolino]

Track the downstream integration that consumes the published amaru-bootstrap-producer image from the Cardano node Antithesis stack and removes the need for a forked or ad hoc Amaru loader path.

Acceptance criteria

• Open or prepare a downstream PR against the Cardano node Antithesis compose stack.
• Use the ghcr.io/lambdasistemi/amaru-bootstrap-producer:<sha> image published by this repository; pin by commit SHA, not by a moving branch or latest tag. Current CI-proven baseline: d33836055256e9c4eac933f6f67902620be8b99f.
• Mount the cardano-node ChainDB read-write into the producer and mount the Amaru bundle volume for the consumers. The producer treats immutable chunks as read-only input, but node-10.7.1 consensus validation requires writable filesystem access while opening ChainDB.
• Configure Amaru services with depends_on: condition: service_completed_successfully on the producer.
• Preserve restart behavior: Amaru restarts reuse the committed bundle; the producer is not rerun on ordinary Amaru process restarts.
• Record a smoke run showing the producer completes and at least one Amaru service starts from the produced bundle.
• Treat the repository Build Gate amaru-run-bootstrap check from CI proof that Amaru starts from the bootstrap bundle #22 as the minimum pre-Antithesis evidence: the bundle must include the ledger snapshots, matching ledger-tip header, chain store, nonces, and snapshots needed for Amaru startup.

Context

• Depends on Publish bootstrap-producer image to GHCR by commit SHA #14 for image publishing and CI proof that Amaru starts from the bootstrap bundle #22 for the repository-level startup proof.
• This is the downstream compose-file work that PR feat: implement amaru bootstrap producer #12 intentionally keeps out of the core producer repository.
• The PR should pin the producer image by commit SHA, not by a moving branch or latest tag.
• The ChainDB mount is intentionally read-write for compatibility with node-10.7.1 consensus code even though the producer only relies on immutable-chain input semantics.